[Show abstract][Hide abstract]ABSTRACT:
Following the Fukushima accident in March 2011, samples of pine trees (Pinus sylvestris) were collected from three sites near the city of Krasnoyarsk (Siberia, Russia) during 2011–2012 and analyzed for artificial radionuclides. Concentrations of Fukushima-derived radionuclides in the samples of pine needles in April 2011 reached 5.51 ± 0.52 Bq kg−1131I, 0.92 ± 0.04 Bq kg−1134Cs, and 1.51 ± 0.07 Bq kg−1137Cs. An important finding was the detection of 134Cs from the Fukushima accident not only in the pine needles and branches but also in the new shoots in 2012, which suggested a transfer of Fukushima cesium isotopes from branches to shoots. In 2011 and 2012, the 137Cs/134Cs ratio for pine needles and branches collected in sampling areas Krasnoyarsk-1 and Krasnoyarsk-2 was greater than 1 (varying within a range of 1.2–2.6), suggesting the presence of “older”, pre-Fukushima accident 137Cs. Calculations showed that for pine samples growing in areas of the Krasnoyarskii Krai unaffected by contamination from the nuclear facility, the activity of the Fukushima-derived cesium isotopes was two–three times higher than the activity of the pre-accident 137Cs.

[Show abstract][Hide abstract]ABSTRACT:
The bioaccumulation of actinide 241Am from food and water in bodies of freshwater
fish (Carassius auratus gibelio, silver crucian carp) has been investigated in
laboratory experiments. Homogenized biomass of submerged macrophytes labeled
with 241Am was injected into the fish gullet. Internal organs and tissues of crucian
carp could be ranked according to activity concentration of dietary 241Am after
depuration of the digestive tract as follows: liver > gonads > bones > muscles.
Accumulation of waterborne 241Am in internal organs and tissues of crucian carp
mainly occurred via the digestive tract. While the concentration of 241Am in liver of
crucian carps decreased during depuration time, its concentration in bones increased
indicating slower transfer of 241Am to skeleton compared to muscles and liver. The
retention of dietary 241Am in the bodies of crucian carp reached 35%�46% of
ingested 241Am: 20%�31% was retained in liver, 0.6%�0.8% in skeleton, and
1.4%�2.0% in muscles. The concentration factor of 241Am from water was 0.4 for the
whole body, 0.3 for liver, 0.01 for muscles, and 0.01 for skeleton. Trace amounts of
241Am were recorded in viscera and muscles of a wild population of silver crucian
carp inhabiting a radioactively contaminated part of the Yenisei River.

[Show abstract][Hide abstract]ABSTRACT:
The laboratory testing of bottom sediments (BSs) from the Yenisei River containing different concentrations of technogenic radionuclides, heavy metals, and biogenic elements (N and P) based on aquatic such plants as Elodea canadensis (Canadian waterweed) and Myriophyllum spicatum (Eurasian watermilfoil) has revealed a higher sensitivity of roots to the general quality of BSs than shoots: shoot length (9%) < root
length (11%) < root number (15%) in M. spicatum; shoot length (22%) < root length (42%) < root number
(44%) in E. canadensis. In contrast to M. spicatum, the growth parameters of roots and shoots in E. canadensis have differed in a significant statistical manner between most BS samples. A reverse correlation has been found between the increase in shoot length and the activity of technogenic radionuclides in BSs, which is mostly significant in E.canadensis (r2 = 0.90–0.95, p = 0.05). Since the growth of shoots and roots in
E. canadensis has turned out to be more sensitive to changes in the quality of BSs than that in M. spicatum, E. canadensis can be considered more prospective for biotesting BSs.

[Show abstract][Hide abstract]ABSTRACT:
Chromosome abnormalities in ana-telophase cells of apical root meristem of aquatic plant Elodea. canadensis (elodea), sampled in 2011-2012 in the Yenisei River at a site with background level of contamination and at several sites on the stretch contaminated with artificial radionuclides, and with chemical pollutants from municipal and industrial discharges of the Krasnoyarsk city. Lowest rate (5.2%) of cells with chromosome abnormalities was registered at sampling site with background level of contamination upstream of the Krasnoyarsk, highest rate of cells with abnormalities (39.7%)-in roots of elodea sampled in bottom sediments with highest concentration of Cs-137. Sum of rates of cells with abnormalities and rates of cells with all types of abnormalities positively correlated with total concentration of artificial and natural radionuclides, with concentration of artificial radionuclides and Cs-137 in bottom sediments of the Yenisei River (r (2) = 0.91-0.96, p < 0.0005 for sum of rates of cells with abnormalities; r (2) = 0.58-0.92, p < 0.05 for all types of abnormalities).

[Show abstract][Hide abstract]ABSTRACT:
It was recently reported that radioactive fallout due to the Fukushima Nuclear Accident was detected in environmental samples collected in the USA and Greece, which are very far away from Japan. In April-May 2011, fallout radionuclides ((134)Cs, (137)Cs, (131)I) released in the Fukushima Nuclear Accident were detected in environmental samples at the city of Krasnoyarsk (Russia), situated in the center of Asia. Similar maximum levels of (131)I and (137)Cs/(134)Cs and (131)I/(137)Cs ratios in water samples collected in Russia and Greece suggest the high-velocity movement of the radioactive contamination from the Fukushima Nuclear Accident and the global effects of this accident, similar to those caused by the Chernobyl accident.

[Show abstract][Hide abstract]ABSTRACT:
The Yenisei River is contaminated with artificial radionuclides released by one of the Russian nuclear plants. The aquatic plants growing in the radioactively contaminated parts of the river contain artificial radionuclides. The aim of the study was to investigate accumulation of artificial radionuclides and stable elements by submerged plants of the Yenisei River and estimate the strength of their binding to plant biomass by using a new sequential extraction scheme. The aquatic plants sampled were: Potamogeton lucens, Fontinalis antipyretica, and Batrachium kauffmanii. Gamma-spectrometric analysis of the samples of aquatic plants has revealed more than 20 radionuclides. We also investigated the chemical fractionation of radionuclides and stable elements in the biomass and rated radionuclides and stable elements based on their distribution in biomass. The greatest number of radionuclides strongly bound to biomass cell structures was found for Potamogeton lucens and the smallest for Batrachium kauffmanii. For Fontinalis antipyretica, the number of distribution patterns that were similar for both radioactive isotopes and their stable counterparts was greater than for the other studied species. The transuranic elements (239)Np and (241)Am were found in the intracellular fraction of the biomass, and this suggested their active accumulation by the plants.

[Show abstract][Hide abstract]ABSTRACT:
Freshwater fishes (Carassius auratus gibelio, crucian carp) were fed through catheter with homogenized biomass of submerged macrophytes labeled with transuranium element 241Am. The intensity of excretion of americium and its accumulation in organs and tissues of fishes were investigated. The highest release of
americium (up to 70%) was recorded on the second day after feeding. 94–98% of americium were excreted during 3–4 days; however, americium was also recorded in the excrements after 11 days. Americium was registered in organs and tissues of fishes, including those tissues that had no direct contact with americium (bones and muscles). This implies assimilation of americium via digestive tract. The activity concentration of americium in bones (11 Bq/kg, fresh mass) was twice as high as that in muscles, heads and external tissues and organs (skin, scales and fins). The highest activity concentration of americium was registered in viscera (33 Bq/kg, 48% of the total activity in the body). Accumulation of americium in muscles enhances
the probability of the further transfer of americium along a food chain.

[Show abstract][Hide abstract]ABSTRACT:
The study addresses the effect of humic substances on marine luminous bacteria Photobacterium phosphoreum exposed to Am-241 (3,000 Bq L(-1), water solution). Luminescent intensity of the bacteria was applied as a marker of their physiological activity. Humic substances have been found to reduce the effect of Am-241 on luminescence, decrease damage to cells, and change distribution of Am-241 between bacterial cells and intercellular media. It was shown that water-soluble humic substances, being products of natural transformation of organic substances in soil and bottom sediments, can serve as protecting agents for water microorganisms exposed to alpha radionuclides.

[Show abstract][Hide abstract]ABSTRACT:
Releases from the nuclear facility Mining-and-Chemical Combine (MCC) located at Zheleznogorsk have contributed to the radionuclide contamination of the Yenisei River since operations commenced in 1958. The aim of this study was to assess the activity concentrations of artificial radionuclides and the strength of their binding in Yenisei River sediments. Investigation of Yenisei River sediment samples revealed the presence of artificial radionuclides typical of the MCC radioactive discharge: namely, isotopes of europium, caesium, Co and transuranium elements. The concentrations of artificial radionuclides in the sediment layers remain relatively high as far as 200 km downstream of the MCC. In sediment cores collected upstream of the MCC, γ-spectrometric measurements registered only one artificial radionuclide, Cs, with a maximal activity of 8 Bq·kg. Sequential extraction performed on samples of the upper layers of the sediment core showed different degrees of potential environmental availability for artificial radionuclides: the highest was recorded for Am and Eu (up to 85% of initial activity), followed by Co (up to 32%), and finally, Cs (up to 15%). In a few samples, Am was present in the unextractable form, which may be accounted for by the presence of reactor fuel microparticles.

[Show abstract][Hide abstract]ABSTRACT:
In this work we experimentally estimated the capacities of the key components of the Yenisei River (Russia): particulate suspended matter (seston), diatom microalgae, and submerged macrophytes for accumulating (241)Am from water. In our experiments large particles of seston (>8mum), comparable in size with diatoms, took up most of americium from water. The accumulation of americium by isolated diatom algae (Asterionella formosa and Diatoma vulgare) was lower than by total seston. The concentration factors (CFs) of (241)Am for seston of the Yenisei River in our experiments were (2.8-6.9).10(5); for diatoms - (1.5-4.2).10(4). The CFs for aquatic plant Elodea canadensis were within the same order of magnitude as those for diatoms. Activity concentration and CFs of (241)Am were nearly the same in experiments under dark and light conditions. This is indicative of an energy independent mechanism of americium uptake from the water by diatoms and submerged macrophytes.

[Show abstract][Hide abstract]ABSTRACT:
A submerged macrophyte of the Yenisei River, Elodea canadensis, was used to study the microdistribution of the artificial radionuclide (241)Am among different components of the plant. The total amount of (241)Am added to the experimental system was 1850+/-31 Bq/L. The total amount of (241)Am accumulated by the plants was 182 Bq per sample, or 758,333+/-385 Bq/kg dry mass. It has been found that the major portion of (241)Am accumulated by E. canadensis, up to 85%, was bound to solid components of the cells. It is observed that the microdistribution of (241)Am within different components of the submerged plant E. canadensis was not uniform. (241)Am distribution vary depending on the age of the leaf blades, the state of the cells and morphological features of the plant stem.

[Show abstract][Hide abstract]ABSTRACT:
The study addresses 242Pu accumulation by Elodea canadensis, one of the abundant species of submerged plants in the Yenisei River. 242Pu in water samples of the "Elodea-Yenisei River water" model system and in the biomass fractions was determined alpha-spectrometrically, following radiochemical recovery of 242Pu using 236Pu--a chemical yield tracer. The experiments on accumulation of 242Pu by Elodea biomass showed that the activity concentration of 242Pu can reach 21 +/- 2 Bq/g dry wt, with the concentration factor for 242Pu 13100 +/- 2100 L/kg dry wt. Results of chemical fractionation proved that during the first few hours of the experiment 242Pu contained in Elodea was mainly concentrated in the exchangeable and the adsorbed fractions of biomass (about 100%). As Elodea biomass accumulated 242Pu, the absolute amount of 242Pu in the exchangeable and the adsorbed fractions remained almost unchanged, although the portion of 242Pu tightly bound to biomass increased. At the end of the experiment, on day 7, 242Pu tightly bound to biomass (fractions of organics and mineral residue) constituted 43-63% (in different experiments) of the total 242Pu in the biomass.

[Show abstract][Hide abstract]ABSTRACT:
The study addresses accumulation of radionuclides by mushrooms and berry shrubs from the forest soil in the 30-km area around the MCC (the Krasnoyarskii Krai, Russia). The Suillus granulatus and S. luteus mushrooms have been found to be the best bioindicators in this area. The level of 137Cs concentration in these species can reach 10 kBq/kg dry mass. The 137Cs transfer factor (TF) by the mushrooms varies 5-fold among the sites that receive radionuclides from different sources. The level of radionuclide activities accumulated by berry shrubs is 2–3 orders of magnitude lower than the activities accumulated by mushrooms. No relationship has been found between the TFs of radionuclides to the shrubs and the pathway via which the radionuclides enter the soil. The contribution of the dose due to intake of mushrooms and berries to the annual effective dose of internal exposure to residents does not exceed 150 μSv/year and 1.4 μSv/year, respectively, estimated from the registered levels of accumulated 137Cs.